Alleviation of the plastic deformation of gel ink under strong stress through an esterification of xanthan gum reinforcing its double helix structure

As a natural organic polymer,xanthan gum(XG)can alleviate the plastic deformation of gel ink under strong stress and realize the reasonable regulation of the rheological properties of gel ink.However,as the double-helix structure connected by hydrogen bonds cannot resist the mechanical environment of strong stress,XG shows poor shear resistance.In this study,a polymer gel with interpenetrating polymer network structure was prepared by esterifying XG,taking polystyrene maleic anhydride(SMA)as the modifier.In addition to retaining the excellent rheological properties of XG,the generated polymer gel also exhibited high shear resistance.The optimal addition amount of the esterification reaction modifier was determined as mXG:mSMA=5:3 according to the gel ink standard.With this amount,the viscosity of the modified xanthan gum(SXG)gel increased to 1578.8 mPa·s and 100.7 mPa·s at shear rates of 4 s1 and 383 s1,respectively,and the shear resistance increased more than 2 times compared to the unmodified one.It is because of the ester bond formed by esterification that the reaction strengthens the interaction between molecular segments,enabling the new gel to resist to strong mechanical stress.The new polymer gel studied in this paper and the proposed mechanism of action provide new insights for the development of high-end gel ink and also provide theoretical support for the study of rheological properties of non-Newtonian fluids.

Complete kinetic model for esterification reaction of lauric acid with glycerol to synthesize glycerol monolaurate

Glycerol monolaurate(GML)is a widely used industrial chemical with excellent emulsification and antibacterial effect.The direct esterification of glycerol with lauric acid is the main method to synthesize GML.In this work,the kinetic process of direct esterification was systematically studied using p-toluenesulfonic acid as catalyst.A complete kinetic model of consecutive esterification reaction has been established,and the kinetic equation of acid catalysis was deduced.The isomerization reactions of GML and glycerol dilaurate were investigated.It was found that the reaction was an equilibrium reaction and the reaction rate was faster than the esterification reaction.The kinetic equations of the consecutive esterification reaction were obtained by experiments as k_(1)=(276+92261Xcat)exp(-37720/RT)and k_(2)=(80+4413Xcat)exp(-32240/RT).The kinetic results are beneficial to the optimization of operating conditions and reactor design in GML production process.

Catalytically active membranes for esterification:A review

Esterification is an important process in the food industry and can be carried out via homogeneous or heterogeneous catalysis.The homogeneous catalyst,despite providing high conversion,can cause corrosion in reactors,which is not observed with the use of heterogeneous catalysts.However,some of these catalysts require a high process temperature and may lose their catalytic activity with reuse.Thus,catalytic membranes have been proposed as a promising alternative.The combination of catalysis and separation in a single module provides greater conversion,reduction of excess reagents,compact industrial plant,making the process more efficient.Within this context,this work aims to present a literature review on the catalytic membrane for the synthesis of esters,improving the understanding of the production and development.This review examines the materials,catalysts used,and synthetic pathways.A comparison between the methods,as well as limitations and gaps in the literature,are highlighted.

Gold/Mg-Al mixed oxides catalysts for oxidative esterification of methacrolein:Effects of support size and composition on gold loading

Gold catalysts supported on Mg-Al mixed oxides for oxidative esterification of methacrolein are prepared by impregnation.Effects of the support particle size,concentration of HAuCl4 solution and Mg/Al ratio on gold loading and catalytic properties are investigated.The catalysts are characterized by CO_(2)-TPD,EDS,XPS,STEM and XRD techniques.Catalysts with smaller support particle size show more uniform gold distribution and higher gold dispersion,resulting in a higher catalytic performance,and the uniformity of gold and the activity of the catalysts with larger support particle size can be improved by decreasing the concentration of HAuCl4 solution.The Mg/Al molar ratio has significant effect on the uniformity of gold and the activity of the catalyst,and the optimum Mg/Al molar ratio is 0.1–0.2.This study underlines the importance of engineering support particle size,concentration of HAuCl4 solution and density of adsorption sites for efficient gold loading on support by impregnation.

Insight into the green route to dimethyl succinate by direct esterification of bio-based disodium succinate using CO_(2)and CH_(3)OH

The fermentation for succinic acid production outperforms other methods by low energy consumption and environmental benignity,with the resulting products mainly as disodium succinate(DSA).By directly esterifying DSA using CO_(2) and CH3OH,it is expected to avoid the use of inorganic acids.By high-resolution mass spectrometry analysis and theoretical calculation,this study establishes that the reaction consists of three steps,i.e.,first forming 3-carboxypropanoate,then monomethyl succinate(MMS),and finally dimethyl succinate(DMS).A detailed kinetic analysis is further performed,the results demonstrate that the transformation of DSA to MMS is regarded to be a second-order reaction for reactant DSA,while the transformation of MMS to DMS is a first-order reaction for reactant MMS.The activation energy for the generation of MMS from DSA is 37.15 kJ·mol^(-1),and that for the generation of DMS from MMS is 85.80 kJ·mol^(-1),indicating the latter one is the rate-determining step.

Conjugation of Candida rugosa lipase with hydrophobic polymer improves esterification activity of vitamin E in nonaqueous solvent

We described a novel polymer-lipase conjugate for high-efficient esterification of vitamin E using vitamin E and succinic anhydride as the substrates in nonaqueous media.In this work,the monomer,N-isopropylacrylamide(NIPAM),was grafted onto Candida rugosa lipase(CRL)to synthesize poly(NIPAM)(pNIPAM)-CRL conjugate by atom transfer radical polymerization via the initiator coupled on the surface of CRL.The result showed that the catalytic efficiencies of pNIPAM-CRL conjugates(19.5-30.3 L·s^(-1)·mmol^(-1))were at least 7 times higher than that of free CRL(2.36 L·s^(-1)·mmol^(-1))in DMSO.It was attributed to a significant increase in Kcat of the conjugates in nonaqueous media.The synthesis catalyzed by pNIPAM-CRL co njugates was influenced by the length and density of the grafted polymer,water content,solvent polarity and molar ratio of the substrates.In the optimal synthesis,the reaction time was shortened at least 7 times,and yields of vitamin E succinate by pNIPAM-g-CRL and free CRL were obtained to be 75.4%and 6.6%at 55℃after the reaction for 1.5 h.The result argued that conjugation with pNIPAM induced conformational change of the lid on CRL based on hydrophobic interaction,thus providing a higher possibility of catalysis-favorable conformation on CRL in nonaqueous media.Moreover,pNIPAM conjugation improved the thermal stability of CRL greatly,and the stability improved further with an increase of chain length of pNIPAM.At the optimal reaction conditions(55℃and 1.5 h),pNIPAM-g-CRL also exhibited good reusability in the enzymatic synthesis of vitamin E succinate and kept~70%of its catalytic activity after ten consecutive cycles.The research demonstrated that pNIPAM-g-CRL was a more competitive biocatalyst in the enzymatic synthesis of vitamin E succinate and exhibited good application potential under harsh industrial conditions.

Liquid-phase esterification of methacrylic acid with methanol catalyzed by cation-exchange resin in a fixed bed reactor:Experimental and kinetic studies

The kinetic behavior of esterification between methacrylic acid and methanol catalyzed by NKC-9 resin was studied in a fixed bed reactor.The reaction was conducted in the temperature range of 323.15 to 368.15 K with the molar ratio of reactants from 0.8 to 1.4 under certain pressure.The measurement data were regression with the pseudo-homogeneous(P-H),Eley-Rideal(E-R),and Langmuir-Hinshelwood(L-H)heterogeneous kinetic models.Independent adsorption experiments were implemented to gain the adsorption equilibrium constants of four components.Among the above three models,the L-H model exhibited the best fitting results.The stability of NKC-9 was evaluated by long-term running with the yield of methyl methacrylate no decrease during 3000 h operation.The structure and physicochemical properties of the new and used catalyst were performed by several characterizations including thermogravimetric analysis(TG),scanning electron microscope(SEM),X-ray diffraction(XRD)and Fourier transform infrared spectroscopy(FT-IR)and so on.

Esterification of acetic acid with isobutanol catalyzed by ionic liquid n-sulfopropyl-3-methylpyridinium trifluoromethanesulfonate:Experimental and kinetic study

As an important organic,isobutyl acetate(IbAc)has been widely used in industries because of its good biodegradability,low surface tension,and other properties.The industrial production of IbAc is usually catalyzed by sulfuric acid.However,the use of sulfuric acid has the drawbacks of causing considerable corrosion to equipment and being difficult to be separated.In this work,n-sulfopropyl-3-methylpyridinium trifluoromethanesulfonate([HSO_(3)-PMPY][CF_(3)SO_(3)])Bronsted acidic ionic liquid(BAIL)was used as the catalyst and the catalytic activity,solubility,and corrosiveness were evaluated for the esterification of acetic acid with isobutanol.The reaction kinetics and chemical equilibrium were systemically studied.Compared to conventional acid catalysts,[HSO_(3)-PMPY][CF_(3)SO_(3)]showed higher catalytic activity,more excellent reusability,more favorable phase separation,and non-corrosiveness.Three kinetic equations based on ideal homogeneous(IH),non-ideal homogeneous(NIH),and modified nonideal homogeneous(NIH-M)models were established and correlated with the experimental data to determine the parameters and errors.The NIH-M model exhibited the best agreement with the experimental data,owing to its prediction considering the non-ideality and the self-catalysis effect of acetic acid in this system.Besides,the error of NIH-M model fitting was mainly caused by the difference in solubility between[HSO_(3)-PMPY][CF_(3)SO_(3)]with reactants and products in the reaction system.Furthermore,the applicability of the NIH-M model was investigated by simulating the esterification of acetic acid with three short-chain alcohols(ethanol,n-butanol,and isobutanol)catalyzed by BAILs.The NIH-M model displayed an acceptable simulation for this type of acetic acid esterification reaction catalyzed by BAILs at different ranges of the BAILs concentration and temperature.This study confirmed the industrial prospects of[HSO_(3)-PMPY][CF_(3)SO_(3)]in isobutyl acetate production and the applicability of the NIH-M kinetic model in the esterification of acetic acid.

Encapsulation of lipases on coordination polymers and their catalytic performance in glycerolysis and esterification

In this study,lipases of CALB(Candida antarctica lipase B),TLL(Thermomyces lanuginosa lipase),RML(Rhizomucor miehei lipase),CALA(Candida antarctica lipase A)and LU(Lecitase?Ultra)were encapsulated into the nucleotidehybrid metal coordination polymers(CPs)for diacylglyerols(DAG)preparation.Guanosine 5'-monophosphate(GMP)and adenosine 5'-monophosphate(AMP)were used as coordinating molecules,and metal ions of Fe^(3+),Ba^(2+),Mn^(2+),Ni^(2+)and Cr^(3+)were applied to prepare matrix.Results indicated that,besides Ba^(2+)with AMP,all other metal ions can coordinate with AMP and GMP to generate CPs.In addition,the AMP/Ni was amorphous when standing temperature was 4℃,while it was crystalline when standing temperature was from 30 to 180℃.DAG content from 47.55%to 64.99%was obtained from glycerolysis by CALB@GMP/Ba,RML@GMP/Ba,TLL@GMP/Ba,RML@GMP/Mn and TLL@GMP/Mn.Additionally,CALB@GMP/Fe showed selectivity towards DAG formation in the esterification and DAG content up to 61.88%was obtained.

Multi-output Gaussian Process Regression Model with Combined Kernel Function for Polyester Esterification Processes

In polyester fiber industrial processes,the prediction of key performance indicators is vital for product quality.The esterification process is an indispensable step in the polyester polymerization process.It has the characteristics of strong coupling,nonlinearity and complex mechanism.To solve these problems,we put forward a multi-output Gaussian process regression(MGPR)model based on the combined kernel function for the polyester esterification process.Since the seasonal and trend decomposition using loess(STL)can extract the periodic and trend characteristics of time series,a combined kernel function based on the STL and the kernel function analysis is constructed for the MGPR.The effectiveness of the proposed model is verified by the actual polyester esterification process data collected from fiber production.

Investigation into Protective Groups for Anilino Functionality upon Oxone-Mediated Oxidative Esterification

In the course of organic synthesis, particularly for multi-step synthesis or natural product total synthesis, the selection of appropriate protective groups for the intended functionality is crucial in order to achieve chemoselective synthetic goals. The development of many useful protective groups has been reported based on the functionality of the anilino group. Herein, we discuss our study of various protective groups and the processes we used to establish compatibility with anilino functionality via the implementation of Oxone-mediated oxidative esterification in methanol. The results and the details of our experiments are reported herein.

丙烯酰胺-柠檬酸改性葵花秸秆吸油材料的制备及吸油动力学

以农业废弃物葵花秸秆为原料,分别用10%氨水、丙酮-环己烷、甲苯-乙醇对葵花秸秆预处理后,采用丙烯酰胺-柠檬酸酯化法对其改性,研究了改性葵花秸秆对油品的吸附性能,开展了吸附热力学及动力学研究,探讨了改性葵花秸秆的吸油机理。结果表明,丙酮-环己烷预处理+改性葵花秸秆对油品的吸油性能最强,其次为甲苯-乙醇预处理+改性葵花秸秆、10%氨水预处理+改性葵花秸秆;改性葵花秸秆对不同油品的吸油性能大小为:大豆油>柴油>原油;丙酮-环己烷预处理+改性葵花秸秆对原油的保油率最高,10%氨水预处理+改性葵花秸秆对大豆油的去除率最高;吸附热力学表明改性葵花秸秆对油品的吸附是以单分子层吸附为主的化学吸附,该吸附过程符合准二级动力学方程。该研究为解决石油污染问题提供了新思路,也为农作物副产物的综合利用提供了方向。

气相色谱法测定猪肉脂肪的脂肪酸方法优化

比较在3种程序升温条件下的37种混合脂肪酸甲酯标准品的谱图,确定最适合分析猪肉脂肪的脂肪酸的程序升温条件;比较索氏提取法、酸水解辅助提取法、有机溶剂浸提法、超声波辅助提取法提取猪肉脂肪,确定最佳猪肉脂肪提取方法;比较碱法甲酯化、酸法甲酯化、碱皂化酸酯化法、碱皂化三氟化硼酯化法对猪肉脂肪的脂肪酸进行甲酯化处理,确定最佳甲酯化方法。结果表明:最适合分析猪肉脂肪的脂肪酸的程序升温条件为在初始温度140℃条件下保持5 min,以5℃/min升温至220℃保持15 min;最佳提取方法是超声波辅助提取法;最佳甲酯化方法是碱法甲酯化。

邻叠氮苯甲酸的“一锅法”合成及其酯化反应

邻叠氮苯甲酸是一类有机合成中常用的原料和反应中间体。以六甲基磷酰胺(HMPA)为溶剂,邻硝基苯甲醛通过叠氮化反应转化为邻叠氮苯甲醛中间体。以新制的氧化银为氧化剂,邻叠氮苯甲醛中间体一锅法室温氧化得到相应的邻叠氮苯甲酸。2-叠氮苯甲酸的酰基化中间体后可顺利转化为酯类化合物,其中的邻叠氮苯甲酸丙酮醇酯经过斯陶丁格/N-维悌希反应环化得到2-甲基-3H-苯并[e][1,4]氧杂环戊烯-5-酮。

一种拉帕替尼衍生物的合成及抗HER2阳性乳腺癌作用研究

目的合成一种拉帕替尼的衍生物,探讨其抗HER2阳性乳腺癌的作用和作用机制。方法以阿司匹林为酰化试剂,应用Steglich酯化反应,经DCC-DMAP催化合成了乙酰化拉帕替尼(化合物Ⅰ)。应用CCK8及平板克隆法考察化合物Ⅰ抗HER2阳性乳腺癌细胞增殖的能力,采用分子对接技术预测化合物Ⅰ的作用靶点,通过Western blot法揭示化合物Ⅰ对BT474细胞AMPK/mTOR通路蛋白的影响。结果化合物Ⅰ的结构经1H NMR、13C NMR和MS确证。化合物Ⅰ对BT474细胞的IC50分别为(112.05±3.21)nmol·L^(-1)(24 h)、(35.87±0.79)nmol·L^(-1)(48 h)和(4.98±0.05)nmol·L^(-1)(72 h);化合物Ⅰ可显著抑制BT474细胞的克隆形成;分子对接结果显示化合物Ⅰ与EGFR、HER2、AMPK、mTOR和AKT1均有较好的结合;Western blot结果显示化合物Ⅰ可显著上调p-AMPK、AMPK,且激动作用较拉帕替尼更强,化合物Ⅰ亦可显著下调EGFR、HER2、p-AKT1、AKT1、p-mTOR和mTOR。结论化合物Ⅰ较拉帕替尼有更强的抗HER2阳性乳腺癌增殖活性,其主要通过激动AMPK,抑制AKT1和mTOR,调节AMPK/mTOR通路发挥作用。

正交设计提高乙酸乙酯合成的产率和纯度

在乙酸乙酯合成的实验教学中,通常使用阿贝折射仪分析产物纯度,误差较大。在本研究中,采用气相色谱内标校正因子法和面积归一化法来测定乙酸乙酯的含量,我们发现内标校正因子法测量的结果准确度高,且操作简单。合成条件为:乙醇、乙酸摩尔比为1.5∶1,浓硫酸的添加量为2 mL。通过正交实验设计优化乙酸乙酯纯化过程,得到最佳纯化条件:20 mL饱和氯化钠溶液、40 mL 100%饱和氯化钙溶液(每次20 mL)、1.8 g无水硫酸镁。在此条件下提纯,我们将实验教学中普遍合成产率55%提高到80.70%,且纯度高达96.69%,实现了乙酸乙酯合成产率和纯度的双向提升。

氯化胆碱改性聚酰胺纳滤膜的制备与分离性能

为了提高传统聚酰胺纳滤膜的分离性能,利用酰氯与羟基之间的酯化反应将带有正电荷的季铵盐氯化胆碱(CC)引入聚酰胺纳滤膜表面,制备在中性条件下具有近中性荷电性的氯化胆碱/聚酰胺纳滤膜,通过对无机盐的分离测试考察了CC质量分数对薄膜复合(TFC)膜性能的影响。结果表明,当CC质量分数达0.10%时,改性效果最佳,TFC膜对Na_(2)SO_(4)、MgSO_(4)和MgCl_(2)均具有较高的截留率,具有改善的Mg^(2+)/Li^(+)分离能力,渗透通量提升了315%。

纤维素制备乙酰丙酸乙酯的研究进展

从纤维素原料入手,总结了合成乙酰丙酸乙酯的多种技术路线。通过技术路线优缺点对比,优选了纤维素直接醇解法,并探究了纤维素直接醇解法下乙酰丙酸乙酯形成的关键反应机理。以催化剂为切入点,指出了制备乙酰丙酸乙酯催化剂的研究进展,讨论了该领域研究存在的3个问题,特别强调了适用生物质种类的选择,展望了催化剂进一步研究的发展方向。

载磺胺嘧啶聚乙二醇前药的制备及抗菌性能研究

以不同分子量的聚乙二醇(PEG)与一氯乙酸为原料,通过酯化反应合成氯乙酰聚乙二醇酯,将它与抗菌剂磺胺嘧啶(SD)结合制备了不同分子量的PEG-SD前药,并进行了红外、核磁和紫外的表征。结果表明,磺胺嘧啶成功接载到聚乙二醇链末端。随着聚乙烯醇的分子量降低,其酯化程度增加,接负SD的比例增加。水解实验表明,PEG-SD前药具有长效缓释抗菌的功能。随着分子量的降低,抑菌效果越好。PEG600-SD对大肠杆菌和金黄色葡萄球菌的最小抑菌浓度分别为31.25μg·mL^(-1)和15.62μg·mL^(-1),具有最好的抑菌效果。

Esterification of cyclohexene with formic acid over a peanut shell-derived carbon solid acid catalyst

A carbon solid acid catalyst was prepared by the sulfonation of partially carbonized peanut shell with concentrated H2SO4. The structure and acidity of the catalyst were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X‐ray diffraction, thermogravimetric analysis, X‐ray photoelectron spectroscopy, and elemental analysis, which showed that it was an amorphous carbon material composed of aromatic carbon sheets in random orientations. Sulfonic acid groups were present on the surface at a density of 0.81 mmol/g. The carbon solid acid catalyst showed better performance than HZSM‐5 for the esterification of cyclohexene with formic acid. At a3：1 molar ratio of formic acid to cyclohexene, catalyst loading of 0.07 g/mL of cyclohexene, and reaction time of 1 h at 413 K, the cyclohexene conversion was 88.4% with 97.3% selectivity to cyclohexyl formate. The carbon solid acid catalyst showed better reusability than HZSM‐5 because its large pores were minimally affected by the accumulation of oligomerized cyclohexene, which deactivated HZSM‐5. The activity of the carbon solid acid catalyst decreased somewhat in the first two recycles due to the leaching of polycyclic aromatic hydrocarbon containing –SO3H groups and then it remained constant in the following reuse.